In the related art, a tire uniformity test for determining good or bad by measuring tire uniformity (uniformity of a tire) and the like has been performed on tires as finished products. For example, in the case of measuring the tire uniformity for a tire for a passenger car, the test is performed using the testing apparatus as illustrated in Patent Reference 1 or the like in the following procedure.
That is, in the tire testing apparatus of Patent Reference 1, the tire flowing from the upstream of an inspection line is sandwiched by rims divided into upper and lower parts, and the tire is inflated in a short time and fixed between the upper and lower rims. After that, by setting the internal pressure of the tire to a test pressure, the rotary drum is pressed against the tire held at the test pressure and is rotated normally or reversely to measure the tire uniformity.
When measuring the tire uniformity in this way, it is necessary to accurately grasp a relation between the pressing position of the tire and the tire load and to correctly generate the target pressing load on the tire. For this purpose, a “load model” illustrating the relation between the pressing position of the tire and the tire load is built, and the tire testing apparatus is controlled, while using the built load model to perform the uniformity test of the tire.
For example, Patent Reference 2 adopts a “spring deformation model” in which a pressing position of a tire and a measured value of a tire load linearly change as a load model for controlling a tire testing apparatus. That is, in the load model of Patent Reference 2, there is disclosed a method for actually measuring the relation between the pressing position and the tire load in advance, calculating the spring constant from the actually measured value, and controlling the pressing load on the assumption that the calculated spring constant is constant.